Some famous Gregories
James Gregorie was the third and youngest son of the Rev. John Gregorie and the brother of David Gregorie of Kinairdy. He was without doubt the greatest bearer of the name Gregorie and is considered to have been one of the most eminent mathematicians of the 17th century, even though he died at the early age of thirty six.
He was born at Drumoak, Aberdeenshire, in November, 1638. His mother Janet observed his interest in mathematics at an early age and taught him herself, with the help of his brother David, before sending him to Aberdeen Grammar School.
He graduated from Marischal College, Aberdeen, in 1657 and from then on devoted himself entirely to science and in particular to researches into the science of optics.
He is perhaps best known for his invention of the reflecting telescope in 1661, when he was only twenty three. This is described, along with the laws of refraction, in his book "Optica promota".
The astronomical telescope invented by Galileo Galilei (1564-1642) and improved by Christiaan Huygens (1629-1695) and others, was a refracting telescope. That is, the observer looked through two or more lenses in order to see a magnified image of a star or planet.
Early astronomers, using refracting telescopes, soon found that stellar images were distorted by two problems inherent in glass lenses — spherical aberration (when light from the edge of a lens is focused to a different point from light from the centre) and chromatic aberration (when different wave lengths of light are refracted to different points of focus), which together produce blurred images with coloured fringes.
Gregorie’s idea was that magnification should be achieved by the use of a concave parabolic primary mirror (which would cure both the above problems), with a smaller elliptical secondary mirror near the point of primary focus reflecting the light back though a hole in the centre of the primary mirror to an eye piece.
He went to London hoping to find a craftsman capable of making his telescope, but it was beyond the ability of even Mr Reive (or Reeve, or Rives), who was regarded as the most skilled lens grinder of the time. Gregorie never succeeded in making his telescope.
Meanwhile, Isaac Newton had independently invented a reflecting telescope which he exhibited at the Royal Society in 1672. This was similar to Gregorie’s design in using a concave primary mirror, but he used a spherical mirror instead of a parabolic mirror, as this was within the capabilities of lens grinders of the period. He also used a plane mirror in place of Gregorie’s elliptical secondary mirror, placing it near the point of primary focus at an angle of 45o with an eye piece to one side. This design eliminated chromatic aberration, but not spherical aberration. Newton was quite willing to admit that his telescope was only a variation on Gregorie’s design but it was simpler and cheaper to make, so it became the standard for the best part of 300 years.
A successful Gregorian telescope was not made until true parabolic mirrors were made by James Short (1710-1768) of Edinburgh — the most celebrated telescope maker of the 18th century.
Most modern astronomical telescopes, for example those at Mount Palomar and Mount Wilson, are made made on Gregorian principles, but the cheap astronomical telescopes made with the amateur in mind are all Newtonian telescopes.
Soon after this, Gregorie turned his attention to mathematics. He corresponded with many of the greatest mathematicians of his day, including Newton, Huygens, Brouncker, Halley, Wallis, Riccioli and Angeli. He lived in Padua, Italy, for three years and published a number of important papers and books. He was elected a Fellow of the Royal Society in 1668.
In 1669 Gregorie returned to London and married his cousin Mary, daughter of George Jameson and widow of John Burnet of Elrick. Towards the end of that year he was elected first professor of the new chair of mathematics at St Andrews University, a post which he held for five years.
In 1674 became first Professor of Mathematics at Edinburgh University.
In October 1675 he was showing some of his pupils the satellites of Jupiter through a telescope when he was suddenly struck blind and died shortly afterwards. After his death his widow was granted a pension of £40 Scots a year by King Charles II.
James and Mary Gregorie had four children:
Helen (1670-1711), James, Janet (1675-?) and Isabel, who lived only a few hours.
James Gregorie, only son of Professor James Gregorie, was born at St Andrews on February 4, 1674, only a year before his father’s death.
The Gregories had been in Edinburgh for only a year when the professor died and Mrs Gregorie therefore returned to her friends in Aberdeen to bring up the children. Like earlier members of the family, James was educated at Aberdeen Grammar School and Marischal College, Aberdeen, before going to Edinburgh to study medicine. He did not graduate from either university but went to the University of Rheims in France, where he graduated MD in 1698.
For the next 26 years Dr Gregorie practised medicine in Aberdeen. Then, when he was nearly 52 years old, he was elected Mediciner (Professor of Medicine) at King’s College, Aberdeen.
Dr Gregorie was twice married. On November 4, 1702, he married Catherine, second daughter of Sir John Forbes of Monymusk. James and Catherine Gregorie had six children: James (b. 1704, died of smallpox 1705); John (b. 1706, died of smallpox 1711); James (1707-1755) (see Rob Roy); Barbara (b. 1709, died of smallpox 1711); David (1711-1739) (See Dunkirk); John (b. 1713, died of smallpox 1714).
Catherine Gregorie died of consumption, (tuberculosis) aged 32, in 1715. James Gregorie was married again in 1719, to Anna, only child of George Chalmers, principal of King’s College. James and Anna Gregorie had three children: George (1720, died unmarried); Christian (b. 1722, died of smallpox 1725); John (1724 - 1773).
John was the youngest son of James Gregorie and was born at Aberdeen on 3 June, 1724.
He was educated at Aberdeen Grammar School, then from 1736 to 1740 he attended King’s College, Aberdeen, where his studies included Latin and Greek, plus the sciences of ethics, mathematics and natural philosophy.
Having completed his studies of the classics to his satisfaction, Gregory decided to take up medicine. After studying at Edinburgh University until 1745, he then went to Leyden, the principal medical school of the time. While at Leyden, he received the unsolicited degree of MD from Aberdeen University and returned to his native city. In 1746, was elected Professor of Philosophy at King’s College, where he lectured in mathematics, moral philosophy and natural philosophy.
In 1749 he resigned his chair at the university in order to devote his time to his growing medical practice. In 1752 he married the Hon. Elizabeth Forbes, daughter of Lord Forbes.
He spent some time in London, where he was elected a Fellow of the Royal Society (FRS), but ultimately settled in Edinburgh.
The death of his beloved wife on 29 September, 1761, left him with a young family. It also apparently drove him to literary work, for all his books were written after this time. His brief nine years of marriage were an extremely happy time for him and he frequently recalled them and referred to them in the years that followed.
Soon after her death, "for the amusement of his solitary hours" as he said himself, Dr Gregory wrote A Father’s Legacy to his Daughters. This little book, written in anticipation of his own early death, was obviously not intended for publication, but was to be given to his daughters after his death.
It was published after his death by his son Dr James Gregory (famous for "Gregory’s Powders"). It was an immediate success, ran into many editions, and was translated into French and Italian. For over a hundred years it was an essential work of reference on every young lady’s bookshelf.
John and Elizabeth Gregory had six children: James (1753-1821), Dorothea Montague (1754-1830), Anna Margaretta (dates unknown), Elizabeth (1757-1771), William, John (1761-1783).
James Gregory was the son of Dr John Gregory (1724-1773) and was born in Aberdeen in January, 1753.
He took up a practice in Edinburgh and, despite the fact that he seems to have been embroiled in constant controversy, he was a very popular doctor. In 1819 his professional income was £2823 plus his university fees of £1378 — very considerable sums on those days.
In 1774 he published his father’s book A Father’s Legacy to his Daughters on behalf of his sisters Dorothea and Anna, for whom it had been intended. A younger sister, Elizabeth, had died in 1771.
Dr Gregory is chiefly remembered for his medicinal concoction known as "Gregory’s Powder" or "Gregory’s Mixture".
According to the British Pharmacopoeia, Gregory’s Powder should be composed of "rhubarb powder 22.2%, magnesium oxide 66.7%, and ginger in powder 11.1%."
Dr Gregory grew Turkish rhubarb in his own garden for this concoction.
Gregory’s Powder has continued to appear in books on therapeutics and materia medica ever since, under its common name and under its official name — Pulvis Rei Compositus 22%.
It is described as a "pale yellow powder, turning red when moistened, prepared as mentioned above, and acting as an antacid, stomachic, and cathartic." There are still many chemists and inhabitants of Aberdeen who can remember preparing it and taking it respectively — the latter with some horror! There are, in fact, reports of it being prescribed in the London area as recently as 1968.
James Gregory married Mary Ross in 1781 but she died in 1784. They had no children.
In 1796 he was married for the second time to Isabella Macleod. They had eleven children: John, Hugh, James Craufurd, William and Donald (twins), Jane Macleod, Elizabeth Forbes, Margaret Craufurd, Georgina, Duncan Farquharson and Isabella.
This line of the Gregory family is still extant, with descendants in various Commonwealth countries. In 1886 Sir Phillip Spencer Gregory (1851-1918) had printed privately his biographical work on the Gregory family "Records of the family of Gregory’, upon which this story is based.